1. Field of the Invention
The present invention relates to a novel crystalline modification of the compound of the formula (I), to processes for its preparation and to its use in agrochemical preparations.

2. Description of Related Art
The compound of the formula (I) is known from EP-A 0 539 588. It can be synthesized by the processes described therein.
In the synthesis process described in the prior art, the compound of the formula (I) of the crystalline modification II (for nomenclature and characterization see further below in the description) is obtained. This crystalline modification is metastable.
It is known that for some polymorphs a certain modification is the thermodynamically stable phase over the entire temperature range up to the melting point, whereas in other substance systems there are one or more transition points in which the stability ratio is reversed. It is not possible to predict the stability ratio and in particular the existence and position of the transition points referred to above. A review of the prior art concerning these basic thermodynamic relations is given in J. Bernstein, R. J. Davey, J. O. Henck, Angew. Chem. Int. Ed., 1999, 38, 3440-3461.
The occurrence of active compounds in various crystalline modifications (polymorphism) is of major importance both for working out preparation processes and for developing formulations. Thus, the various crystalline modifications of a chemical compound differ not only in appearance (crystal habit) and hardness but also in numerous further physicochemical properties. Differences relating to the stability, the filterability, the grindability, the solubility, the hygroscopicity, the melting point, the solids density and the flowability can have a considerable influence on the quality and the efficacy of crop treatment compositions. It has not been possible to date to predict the occurrence and the number of crystalline modifications, including their physicochemical properties. Especially the thermodynamic stability and also the different behaviour after administration in living organisms cannot be determined in advance.
Metastable crystal modifications, such as the crystalline modification II of the compound of the formula (I), generally have disadvantages compared to a thermodynamically stable form with respect to the preparation process, and also with respect to storage and the transport of the active compounds and formulations. It is known from J. Halebian, W. McCrone, J. Pharm. Sci. 58 (1969) 911, that, when a thermodynamically metastable form is used, there may be complete or partial conversion into another polymorphic form during preparation or storage. As an associated phenomenon, unwanted crystal growth (recrystallization), changes in bioavailability, agglomeration, etc., are observed. The conversion may take place over a relatively long period of time or spontaneously and cannot be predicted. Whether, when and in what amount another crystal modification is formed is essentially a matter of chance. This behaviour of metastable crystal modifications may have a large influence on development, transport and in particular on storage stability.